Coated tools, such as cutting tools, have been known in which a diamond layer composed of diamond is deposited on a surface of a base material. Although high hardness of the diamond layer has improved wear resistance, a state in which diamond particles protrude beyond a surface of the diamond layer has occurred in some cases along with grain growth of the diamond particles. On this occasion, ingredients of a work material have been caught in the diamond particles protruding beyond the surface of the diamond layer during a cutting process, and cutting resistance has increased. Consequently, peeling-off of the diamond layer and chipping have occurred.
For example, Patent Document 1 discloses a cutting tool in which a crystalline diamond layer and a nanodiamond layer having a mean particle size of 1-50 nm are sequentially deposited onto a surface of a base material made of cemented carbide.